Hello,
One my the sites I work with, http://www.oransi.com, has seen a significant decrease in crawl Googlebot activity in the last 90 days. See screenshot.
This decrease in crawl stats runs in conjunction with less Kb downloaded per day & an increase in how much time it took Google to download a page.
The client did just go through a redesign, however that happened on 4/16/15, which was after the decrease in Googlebot activity, so that should not be the issue. Same could be said for the mobilegeddan algorithm change.
Any help would be greatly appreciated.